Study Of CVD Growth Mechanism And Laser Properties Of CsPbBr₃ Single Crystal Microcavity Structure

Metal halide perovskite semiconductor material has received extensive attention in solar cells,light-emitting diodes,lasers and many other fields due to its excellent optical and electronic properties,such as low density of trap states,high absorption coefficients,large carrier mobility and many other advantages.What’s more,by changing its composition,we are able to adjust the wavelength of its luminescent.Compared with traditional organic inorganic perovskite materials,Cs Pb X₃（X=Cl,Br and I）metal halide perovskite with inorganic cesium ions has better thermal stability and chemical stability,which is of great significance for realizing high performance light-emitting devices.In this paper,the CVD preparation process,growth mechanism and optical properties of all-inorganic metal halide perovskite Cs Pb Br₃ were studied.Besides the gain medium to produce laser,the natural microcavity structure of Cs Pb Br₃ crystal prepared by CVD method is also used as the resonator.In this paper,the growth mechanism of Cs Pb Br₃ microcavity deposited by CVD method is studied in detail,and the optical characteristics of microcavities with different morphologies are compared.The main contents are as follows:（1）Use tubular furnace,vacuum pump and other equipment set up a simple CVD deposition system.The Cs Pb Br₃ perovskite crystal was deposited on different substrates by CVD method.By changing different experimental conditions,different shapes of microcavities,such as hemisphere,cube and cuboid,were fabricated on the substrate.（2）In the process of preparing Cs Pb Br₃ microcavity by CVD,the effects of substrate position,deposition temperature,substrate type,air pressure and other experimental conditions on the deposition rate and the final morphology of Cs Pb Br₃microcavity were investigated.It is found that the deposition rate is significantly affected by the above external experimental parameters,and Cs Pb Br₃ crystal can grow orderly along the lattice direction of the substrate only at a suitable rate.（3）A series of optical microscope test optical paths were set up.The pump laser source was focused on the microcavity structure.While observing the micro morphology of the sample surface,the photoluminescence（PL）spectra and time resolved photoluminescence（TRPL）spectra under different excitation powers were tested at the same time.The results show that the excitation thresholds of microcavities with different morphologies on（100）silicon,（111）silicon and ITO substrates are respectively 20.0μJ/cm²、11.5μJ/cm²、21.0μJ/cm² and Q factors are 1279.8,1257.9and 300.9 respectively.The stimulated emission fluorescence lifetime is within 10 ps,and the spontaneous emission fluorescence lifetime is between 100 ps and 200 ps.